The present invention relates, in general, to a method for automatically analyzing crude petroleum oils using a spectroscopic technique and, more particularly, to an on-line analysis method of crude petroleum oils, which brings about a significant improvement in analysis accuracy and in an economical aspect. In the present invention, a near infrared (NIR) spectroscopic analysis apparatus is combined with an ordinary distillation apparatus, so as to analyze the physical properties of each oil distillate as soon as it is separated from crude oils.
For oil refineries, where crude oils are refined to produce high value-added products, it is very important to know information about the crude oils to be treated. There are almost no oil refineries that treat only one kind of a crude oil. Indeed, they refine up to tens of kinds of crude oils per year. To this end, most of the oil refineries have been equipped with analysis apparatuses for crude oils and have engaged a great deal of manpower in obtaining up-to-date analysis data for crude oils. Recently, detail assay data(Full Assay Data) which has information about heavy distillates is required as heavy oil cracking facilities are widely introduced. In order to produce full assay data, highly expensive distillation and analysis apparatuses are needed, along with much manpower. Usually, the full assay data, for example, is made by distilling crude oil to more than 10 fractions and analyzing each of the oil fractions for more than 10 physical properties. It typically takes a time of 1-2 weeks to produce full assay data, and about 30% of the period is needed to separate oil fractions through distillation while the remaining 70% is set aside for the analysis of physical properties of each fraction.
As a result of the intensive and thorough research on the crude oil analysis, repeated by the present inventors aiming to reduce the manpower and time period required for the crude oil analysis, it was found that spectroscopy can be introduced to analyze the physical properties of crude oils. In this regard, a physical property-predicting model was established from the spectrometric data from an oil distillate on the basis of the chemometrics theory. By comparing spectrometric data obtained from a target distillate with those of the model, the target distillate could be assayed for physical properties rapidly and accurately. This spectroscopic technique exceptionally reduces the time period required for the analysis of crude oils, compared with conventional assay techniques. Indeed, the measurement of the physical properties of crude distillates can be completed as soon as the crude distillates are separated. In addition, because only a small amount of the distillates are demanded for the spectroscopic measurement, the time period that it takes to distill crude oils is greatly reduced. Accordingly, a significant reduction can be brought about in the amount of analysis equipment as well as the manpower. However, some trace components and physical properties of heavy residue remain unable to be assayed by the spectroscopic method of the invention. Thus, they can be analyzed in conventional manners.
It is therefore an object of the present invention to provide an automatic method for analyzing crude petroleum oils, which utilizes a spectrometric technique in combination with a distillation apparatus in measuring physical properties of crude petroleum oils with the aim of reducing as much equipment cost, manpower and time necessary for the analysis of crude petroleum oils as possible.
Based on the present invention, the above object could be accomplished by a provision of an automatic analysis method of crude oils, using spectroscopy, comprising the steps of: providing analysis equipment comprising: a distillation apparatus comprising: a vacuum part; a heating part; a separation column part; a liquified gas-collecting cylinder having absorbance spectrum-measuring cells; and a distillate-collecting part having a plurality of distillate-collating cylinders; a spectroscopic analyzer comprising: a spectroscope 10 for separating and providing light beams by wavelengths; a measuring cell 9 for measuring samples for absorbance at predetermined wavelengths; and a fiber optic for connecting the spectroscope to the measuring cell; and a physical property predicting model; measuring gaseous components for absorbance at predetermined wavelengths in an on-line manner in the liquified gas-collecting cylinder, said gaseous components being distilled at the first time from a crude oil sample; measuring various distillates of the distillate-collecting cylinders, in sequence, for absorbance at predetermined wavelengths; predicting physical properties of the crude sample from the spectrum data on the basis of the chemometrics theory; and producing assay data for crude oils from the predicted physical properties.